It gets better and better. Here's yet another Bill Munns interview, with further explanation and speculation by Mr. Munns.
At 12:50, Bill discusses that the newly "discovered" film is either a rehearsal or, in his opinion, more likely a recreation of the actual PGF, after the event.
In the new footage is a man on horseback with a rifle, pretending to be Bob Gimlin. There's someone in a "modestly halfway decent suit, nothing spectacular" walks thru the woods "virtually duplicating to the nth degree the PGF."
Bill points out that in this film the Patty subject raises the foot straight up and down and you see the whole bottom of the foot. "And it's pure white exactly like Cibachrome print #72 of the PGF, and it's virtually identical."
The producers of the documentary asked Bill's opinion of the footage and he said "A, it's obviously a man in a suit. The suit isn't anything spectacular. It's not like an off the rack Halloween costume that Phillip Morris would sell. It was custom made for this filming, but it's not Rick Baker, Stan Winston, John Chambers Hollywood quality. It's not anywhere near that. I'd say it's a medium grade proficiency making the suit."
Bill actually held the "new" film, and he gave them details they didn't have before. It was 1966 mfg (but the shooting/exposure date is unknown.
The fact the costume has white feet is telling, as it matches the overexposure seen in reproduced prints. Per Bill, no serious costume would utilize white feet.
I'm half ways thru, I've more to see, but wanted to share this additional interview with you.